[Frequency and distribution of aneuploidy in human gametes: differences as a function of sex]

The frequency and the distribution of aneuploidies were analysed in both spermatozoa and mature oocyte. The present study has pooled 13,975 human sperm chromosome complements and 1,897 oocyte chromosome complements examined to date. The overall frequency of aneuploidy is 10% in spermatozoa and 22.4% in oocytes. Human sperm is characterized by a significant excess of hypo-haploidies and an equitable distribution of aneuploidies among all chromosome groups, whereas mature oocytes display an equal ratio of hypo-haploidies: hyper-haploidies and a high variability in the distribution of non-disjunctions; in the A, B, C and especially in D and G groups, there is a significant difference between the observed and estimated rates of non-disjunction and the frequencies expected from an equal partitioning of non-disjunctions among all chromosomes. This indicates that non-disjunction is not a random event in female meiosis, and consequently that there are differences in the meiotic process between the sexes.